“An evaporite sequence from ancient brine recorded in Bennu samples”. Nature (2025). https://doi.org/10.1038/s41586-024-08495-6
In a groundbreaking study published in Nature on January 29, 2025, scientists have unveiled remarkable findings from samples collected from the asteroid Bennu. These samples provide unprecedented insights into the early solar system’s chemistry and the potential origins of life on Earth.
Asteroid Bennu, a near-Earth object, has been the subject of intense study due to its pristine condition, believed to be preserving materials from the solar system’s formation over 4.5 billion years ago. In 2020, NASA’s OSIRIS-REx spacecraft successfully collected samples from Bennu’s surface and returned them to Earth in 2023. These samples have since been the focus of extensive analysis by researchers worldwide, some of the key findings to date are,
- Evaporite Minerals
The study reports the discovery of evaporite minerals within the Bennu samples. Evaporites form when water evaporates, leaving behind mineral deposits. This indicates that liquid water once existed on Bennu or its parent body, leading to the precipitation of these minerals. Such minerals suggest that Bennu experienced aqueous alteration processes, altering our understanding of the thermal and chemical history of small bodies in the solar system.
- Organic Compounds
Alongside evaporite minerals, the samples contain complex organic compounds, including amino acids and hydrocarbons. These organic molecules are fundamental to life, their presence in Bennu supports the hypothesis that the building blocks of life may have been delivered to Earth via asteroid impacts. This finding aligns with previous studies suggesting that organic-rich asteroids could have contributed to the prebiotic chemistry necessary for life to emerge on our planet.
- Isotopic Analysis
Isotopic studies of the samples reveal a composition consistent with the early solar system’s molecular cloud. The ratios of isotopes, such as hydrogen and nitrogen, provide clues about the conditions under which these materials formed. The data suggest that Bennu’s parent body incorporated interstellar and solar nebula materials, offering a snapshot of the diverse chemical environment present during the solar system’s birth.
- Implications for Astrobiology
The detection of both water-related minerals and organic compounds in Bennu’s samples has significant implications for astrobiology. It supports the theory that essential ingredients for life are widespread in the solar system and that asteroids like Bennu could have played a crucial role in delivering these components to early Earth. This enhances our understanding of the potential for life elsewhere in the solar system and informs future missions targeting asteroids and other small bodies.
The conclusions from this early study.
The analysis of samples from Bennu has provided valuable insights into the early solar system’s chemistry and the potential pathways for the emergence of life on Earth. The discovery of evaporite minerals indicates past interactions with liquid water, while the presence of complex organic compounds underscores the role asteroids may have played in seeding our planet with life’s building blocks. These findings, potentially, deepen our understanding of Earth’s life origins and also guide future explorations in the quest to find life beyond Earth.